Secondary-clock system.



A.L..VSOHM.

' sscoymv CLOCK SYSTEM.

APPUICATION- FILED MAY 21. 191].

1,302,604. Patented May 6,1919.

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ALFRED L. SOHH, OF CHICAGO, ILLINOIS, ASSIGNOB TO SOHM ELECTRIC COMPANY,OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SECONDARY-CLOCK SYSTEM.

Specification of Letters Patent.

Patented May 6, 1919.

To all whom it may concern:

Be it known that I, ALFRED L. Sonar, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Secondary-ClockSystems, of which the following is a full, clear, concise, and exactdescription, reference being had to the accompanying drawings, forming apart of this specification.

The present invention relates to a secondary clock system.

eretofore in the art it has been found very diflicult to keep thesecondary clocks in exact synchronism with the master clock because ofthe occasional occurrence of double contacts. No matter how carefullyconstructed the contact mechanism of the clock may be, double contactswill occur, even if at infrequent intervals. This may be due to the factthat the springs vibrate, or it may occur because of the slight reverserotation of the minute shaft which occurs through the actionof theescapement. This reverse rotation, which occurs at the end of each beat,may bring the moving contact either to the point where it just touchesthe stationary contact and is again withdrawn or it may bring thecontact to the point where it is just leaving the stationary contact,Where the double contact will occur.

The object of this invention is to provide an electrically operatedsecondary clock actuating system, which shall be proof against double orfalse impulses, and which shall be simple in construction and positivein action.

The invention also aims to simplify clock construction by providingnovel means and by eliminating-fine and coarse adjustment whichheretofore have been found necessary.

In the accompanying sheet of drawings, I have illustrated an apparatusembodying the present invention. Figure l is a plan view of a relaymechanism used in the improved clock system.

Fig. 2 is a side elevation of the same.

Fig. 3 is a fragmentary detailed view, showing the manner in which thedetent engages the armature of one of the electromagnets.

Fig. 4; is an enlarged detailed view showing the rear face of thearmature shown in Fig. 3.

Fig. 5 is a circuit diagram of the system.

In Fig. 5 I have shown a plurality of secondary clocks which areoperated by a master clock, not shown in the drawings but indlcateddiagrammatically by means of the time controlled shaft 7 bearing the cam8. The shaft 7 may be the second hand arbor of the clock or may bedriven in unison therewith, as it is customary to advance the clock 6upon the completion of each minute.

Cam 8 is snail shaped and bears a contact 9, which forms an intermediatestep between the outermost dwell 10 and the innermost dwell 11 of thesnail cam. A air of springs 12 and 13 are secured in a blhck ofinsulation 14 and suspended from a pivot 15 so that these springs mayrise and fall with the rotation of the cam. The spring 12 is made longerthan spring 13 and the end of the spring 12 is slightly higher.

As the cam 8 rotates in a clockwise direction, the springs 13 and 12successively make contact with the step 9, which is connected by meansof wire '16 to one side of the battery 17. The spring 13 is connectedwith one terminal of the electro-magnet 18, the other terminal of theelectro-magnet 18 being connected to the other side of the battery 17.The spring 12 is connected to one terminal of the electro-magnet 19, theother terminal of this magnet being also connected to battery 17 so thatcontact of the springs 13 and 12 with the contact step 9 of the camenergizes the magnets 18 and 19 in turn.

The armature 20, is pivoted at its lower edge at 21 by means of screws22 passing through lugs in the base 23 upon which both electro-magnetsare mounted. An I-shaped spring 24 shown partly in dotted lines in Fig.2 serves to retract the armature 20 from the electro-magnet 18 when itis in a non-energized condition. The armature 20 bears a spring 25 whichextends upwardly and registers with 'a contact screw 26 fastened in ayoke 27 secured to but insulated from the base 23. The spring 25 isprovided with a slot 28, through which passes a detent or catch 29,forming an extension of the armature 30 of the electro-magnet 19. Aspring 31 tends to hold the detent 29 against the armature 20 as shownin Fig. 2 in order to hold the contact spring 25 against the stationarycontact 26. The armature 20 has a notch or cut away portion 32 in whichthe end of the detent 29 rests when the armature 20 is in the retractedposition. At this time the contacts 25 and 26 are not in engagement. Thenotch 32 furnishes an incline over which the end of the detent 29 mustpass before the contact 25 and 26 can come into engagement and offerssufiicient resistance to i'event the contacts being jarred together byaccident.

The armature 30 is pivot-ally mounted on the standards 33 which alsofurnishes a support for the electro-magnet 18. Suitable binding posts,as shown in Figs. 1 and 2, are provided on the base 23 for the terminalsof the electro-magnets and of the contacts. An adjusting screw 34 foradjusting the tension of the spring 24, governing the armature 20,

' is also provided.

It can now be seen that as the cam 8 rotates in a clockwise direction,the spring 13 will drop off of the upper dwell 10'upon the intermediatedwell 9 where contact will be made and the circuit for theelectro-magnet 18 will be closed. The electro-magnet 18 attracts itsarmature 20 closing the contacts 25 and 26 which govern the circuit ofthe secondary clocks 6. When the armature 20 is attracted, the latch 29holds the same in position to retain contacts 25 and 26 in engagement.As the cam 8 advances the spring 13 will drop oil of theintermediate'dwell 9 and the spring 12 will make contact with saidintermediate contact. The circuit of the release electro-magnet 19'isthen closed and the armature 20 is released, the contacts 25 and 26separating at this time under the influence of the spring 24. Q

The circuit of the clocks 6 remains closed for a definite period of timefor each revolution of the cam 8, the period of time depending upon thespacing of the springs 12 and 13 but the same being invariably uniform.It has been found very difficult to avoid the making of double contactsin operating a master clock, due to the slight reverse rotation of thesecond hand arbor 7 in the ordinary master clock. If the break betweenthe spring and the rotating contact occurs just at the point where theescapement gives a slight backward rotation to the shaft 7, the contactwill firstbe made on the forward movement of the escapement and then bebroken on the slight reverse rotation, and in this manner two impulseswill be sent when only one should have been transmitted to the secondaryclocks.

A similar condition obtains if the rotating contact is just passing outof contact with the spring and the slight reverse rotation of the shaft7 again brings the rotating contact against the spring, giving a doubleimpulse. The structure that I have shown not only avoids the abovemaking of double contacts, but securely guards against any such actionor any other accidental making of double contacts. When the spring 13drops down on the intermediate dwell 9, the slight reverse rotation,which might cause a break if the contact surface and the cam werecylindrical, cannotoccur because the end of the spring 13 strikesagainst the radial wall of the cam. As soon as the spring 13 drops offof the intermediate dwell 9, the spring 12 will be brought intoengagement with the intermediate dwell 9 and any reverse rotation, whichwo ld tend to bring the spring 13 in contact with the contact 9, formingthe intermediate dwell would cause the end of spring 12 to strike theradial portion of the cam. It can be seen that double contacts areavoided but even if'the same should be made, no false eperation of thesecondary clocks would occl as the armature 20 of the circuit closingmagnet 18 is held in attracted position by means of the detent 29 untilit Is positively released by the energization of the magnet 19. Nomatter how many times the circuit may be made through the magnet 18 thecontacts 25 and 26 will be operated only once until the released magnet19 is energized and no matter how many energizations of the magnet 19occur,

they are all ineffective for closing the conmagnet for closing asecondary circuit, a

latch for holding said circuit closed, a release magnet for opening saidcircuit, two sprlng contacts, one longer than the other adapted to dropin succession from the high dwell of the cam to the intermediatecontact, the shorter contact adapted toenergize the circuit closingmagnet andthe longer one to energize the release magnet, the springsadapted to engage the shoulder of the cam above the intermediate contactto prevent retrograde movement of the cam.

2. In a mechanism for controlling a secondary clock circuit, a. masterclock having a rotatable shaft, a snail cam having a nonconductingperiphery and mounted upon said shaft, an electrical contact dwell onthe cam intermediate the high and the low dwells thereof, two springs,one longer than the ther adapted to successively drop from the highdwell to the intermediate contact and adapted thereby to successivelyenergize a secondary c1rc-u1t closing magnet and a secondary clrcuitrelease magnet, the springs adapted to engage the shoulder of the camcessively close upon said contact as the cam rotates, and meanscooperating with said terminals to prevent retrograde movement of thecam immediately after the terminals close upon said contact.

4. In a clock System f the kind described, a master clock havingarotatable snail cam with a contact for controlling a secondary circuit,a movable terminal adapted to drop upon said contact to close asecondary circuit as the cam rotates in one direction, and a shoulder onthe cam above said cGYitaet adapted to engage the end of the terminal toprevent retrograde movement of the cam, and a second terminal adapted tocontact with the contact n the cam as the first terminal leaves same toopen the secondary circuit.

5. In a clock-system of the kind described, a secondary circuit closingmagnet having a spring held armature movable to secondary circuitclosing position when the magnet is energized, a latch for retaining thearmature in circuit closing position, a release magnet for releasing thearmature to open the secondary circuit, a master clock having a snailcam for controlling the secondary circuit,

anelectrical contact on said cam, a terminal for the closing magnetcircuit and a terminal for the opening magnet circuit, the two terminalsadapted to contact in succession with the contact on the cam tosuccessively close their respective circuits for predeterminedindependent periods of time.

In Witness whereof, I hereunto subscribe my name this 17th day of May A.D. 1917. ALFRED L. SOHM.

